1. Field of the Invention
The present invention relates to a paper sheet feeding apparatus for feeding a recording paper sheet, which may be incorporated in a recording apparatus used with a communication apparatus, information processing apparatus, and the like.
2. Description of the Related Art
Various methods for feeding paper sheets one by one have been used in paper sheet feeding apparatuses mounted in recording apparatuses for use with communication apparatuses, information processing apparatuses, and the like. In one method, the bottom plate of a cassette in which a stack of recording paper sheets is placed is pushed upward by a spring or the like, and both edges of the forward end of the recording paper sheets in the paper sheet feeding direction are pressed by pawls; in this condition, the recording paper sheets in the cassette are advanced in the paper sheet feeding direction by means of a paper sheet feeding roller, and the uppermost sheet of the recording paper sheets is fed out of the cassette when the advancing force of the uppermost paper sheet overcomes the pressing force being applied by the pawls. In another method, a recording paper sheet is fed to a position between a paper sheet feeding roller and a resisting member mounted in contacting relationship to the paper sheet feeding roller, the resisting member being made of rubber or other material having a large friction coefficient, and only the uppermost sheet contacting the paper sheet feeding roller rotating in the paper sheet feeding direction is fed out when the advancing force of the uppermost paper sheet overcomes the resisting force of the resisting member. In a further method, a roller rotating in the paper sheet feeding direction is disposed on the outer surface side of the paper sheet to be fed, and a roller rotating in the direction opposite to the paper sheet feeding direction is mounted on the bottom surface side of the stack of recording paper sheets held in the cassette, the roller rotating in the direction opposite to the paper sheet feeding direction thus acting to push back under recording paper sheets except the uppermost one, while allowing only the uppermost one of the paper sheets to be fed out. In a still further method, only the uppermost paper sheet to be fed is lifted by a vacuum, while holding back the under paper sheets by a vacuum force being applied by a vacuum device from the opposite side, thereby allowing only the uppermost recording paper sheet to be fed out.
Besides the above-described recording paper sheet feeding methods, there is also used an angular separation method in which recording paper sheets are separated and fed out by using a back plate having a supporting face for supporting the recording paper sheets thereon, in combination with a bottom plate mounted at a predetermined angle to the back plate on the downstream side thereof along the recording paper sheet feeding direction and used to separate the recording paper sheets. A paper sheet feeding apparatus using the angular separation method can accomplish the separation and feeding of recording paper sheets with a simple construction. Furthermore, since a recording paper sheet feeding apparatus using the angular separation method, despite its simple construction, can handle recording paper sheets with a variety of thicknesses and requires less mounting space, the installation space of a recording apparatus equipped with such a paper sheet feeding apparatus, and hence the floor space of a communication apparatus or information processing apparatus using the recording apparatus, can be reduced. Moreover, if the paper sheet feeding roller for feeding the recording paper sheet is formed, for example, in a semicircular shape, the paper sheet feeding roller does not contact and apply a load to the sheet being fed out once the sheet is separated and fed from the stack of recording paper sheets. This offers the advantage of being able to smoothly feed out the sheet for printing. These and other advantages have lead to the widespread use of the angular separation method.
While the angular separation method offers various advantages, it does not necessarily provide a perfect solution when it comes to reliably feeding recording paper sheets of a wide variety of thicknesses one by one. A prior art technique addressing this deficiency is disclosed, for example, in Japanese Unexamined Patent Publication JP-A 9-12168 (1997). In this prior art, an auxiliary separation plate formed from an elastic member is provided in addition to the fixed angle bottom plate (also called a separation plate in the prior art), and this auxiliary separation plate is constructed to contact the recording paper sheet at a more acute angle than the separation plate does. At the downstream side of the recording paper sheet as viewed in the recording paper sheet feeding direction, the auxiliary separation plate flexes so that its angle increases, which in turn reduces the recording paper sheet feeding resistance; on the other hand, at the upstream side as viewed in the recording paper sheet feeding direction, the auxiliary separation plate does not flex much, so that its angle remains small, providing large recording paper sheet feeding resistance. In this way, by utilizing the flexing action of the auxiliary separation plate, reliable recording paper sheet separation and recording paper sheet feeding operations can be performed on recording paper sheets of various thicknesses.
The above prior art has the following problem. When the user of the paper sheet feeding apparatus loads a stack of recording paper sheets into the paper sheet feeding apparatus, if the stack of recording paper sheets is inserted into the paper sheet feeding apparatus attended with an impact force, the recording paper sheet may cross the boundary between the back plate and the separation plate, and the lower edges of some of the inserted recording paper sheets may ride over the separation plate. With the lower edges of some of the recording paper sheets riding over the separation plate, if a recording paper sheet feed operation is started, more than one recording paper sheet will be fed out simultaneously, because the recording paper sheets already riding over the separation plate cannot be separated one by one by the separation plate.
The recording paper sheet separation and feeding method using the separation plate and auxiliary plate of the prior art ensures that recording paper sheets are fed out one by one even in the case of recording paper sheets with a wide variety of thicknesses, provided that the recording paper sheets are loaded properly into the paper sheet feeding apparatus; however, when the user has loaded the recording paper sheets into the paper sheet feeding apparatus in such a manner as to cause the lower edges of some of the sheets to ride over the separation plate, the recording paper sheets cannot be properly separated and fed out one by one.
It is an object of the invention to provide a paper sheet feeding apparatus capable of reliably separating and feeding out recording paper sheets one by one immediately after the recording paper sheets are loaded, even when the recording paper sheets are inserted into the paper sheet feeding apparatus attended with an impact force. It is another object of the invention to provide a recording apparatus equipped with such a paper sheet feeding apparatus.
The invention provides a paper sheet feeding apparatus comprising:
a back plate having a supporting face, arranged so as to slope down toward a downstream side in a paper sheet feeding direction;
resilient supporting means, disposed near a lower part of the back plate, for resiliently supporting a lower edge of a stack of recording paper sheets resting on the back plate;
a bottom plate, disposed downstream of the resilient supporting means in the paper sheet feeding direction, for guiding the recording paper sheets; and
a paper sheet feeding roller for feeding out an uppermost sheet of the stack of recording paper sheets by contacting an uppermost recording paper sheet of the stack of recording paper sheets held on the supporting face.
According to the invention, since the resilient supporting means for resiliently supporting the lower edge of the stack of recording paper sheets resting on the back plate is provided near the lower part of the back plate, if the user inserts the recording paper sheets into the paper sheet feeding apparatus attended with an impact force, the resilient supporting means can absorb the impact force applied when inserting the recording paper sheets. Accordingly, since the impact force generated in inserting the recording paper sheets into the paper sheet feeding apparatus is alleviated by the provision of the resilient supporting means, the recording paper sheets can be prevented from riding over the bottom plate, thus avoiding a situation where a plurality of sheets are fed out simultaneously.
In the invention, it is preferable that the resilient supporting means includes:
a rocking support piece whose downstream end portion in the paper sheet feeding direction is supported so as to be angularly displaceable about an axis extending perpendicularly to the paper sheet feeding direction, and whose upstream end portion as viewed in the paper sheet feeding direction is positioned rearwardly of the supporting face of the back plate, and
a spring for applying an upwardly directed spring force to the upstream end portion of the rocking support piece, and thereby pressing the upstream end portion of the rocking support piece against a predetermined position with a stack of recording paper sheets held in a stationary condition, and the following relation is satisfied:
xcex81 greater than xcex82, 
wherein xcex81 represents an angle which a receiving face of the rocking support piece makes with the supporting face of the back plate when the stack of recording paper sheets is held in the stationary condition, and xcex82 represents an angle which the supporting face of the back plate makes with a guide face of the bottom plate.
According to the invention, since the resilient supporting means includes the spring and the angularly displaceable rocking support piece, when the recording paper sheets are inserted into the paper sheet feeding apparatus attended with an impact force, the rocking support piece is displaced angularly to absorb the impact force, and when the impact force is released, the rocking support piece is restored to the predetermined position where the angle that the receiving face of the rocking support piece makes with the supporting face of the back plate when the stack of recording paper sheets is held in the stationary condition is held at xcex81. Accordingly, when the recording paper sheets are inserted into the paper sheet feeding apparatus, the recording paper sheets are prevented from riding over the receiving face of the rocking support piece by the impact force generated at the time of insertion, and further, since, when the recording paper sheet separation and feed operation is started, the angle that the receiving face of the rocking support piece makes with the supporting face of the back plate is held at the predetermined suitable angle xcex81, the recording paper sheet can be reliably separated and fed out one sheet at a time. Furthermore, since the angle xcex81 that the receiving face of the rocking support piece makes with the supporting face of the back plate is greater than the angle xcex82 that the supporting face of the back plate makes with the guide face of the bottom plate, the recording paper sheets separated for feeding are fed out smoothly without a hitch along the guide face of the bottom plate.
In the invention, it is preferable that a plurality of rocking support pieces are disposed spaced apart in a direction perpendicular to the paper sheet feeding direction.
According to the invention, the number of rocking support pieces that support the lower edge of the recording paper sheets differs according to the size of the recording paper sheets to be fed. This means that the force resistant to the feeding of the recording paper sheets, which is generated by the contact of the receiving faces of the rocking support pieces with the lower edge of the recording paper sheets, is adjusted according to the number of rocking support pieces that support the lower edge of the recording paper sheets. Accordingly rocking support pieces whose number is appropriate to the size of the recording paper sheets contacts the lower edge of the recording paper sheets with the result that the separation and feed of the recording paper sheets is smoothly carried out.
In the invention, it is preferable that a serrated portion with serrations arranged in the paper sheet feeding direction is formed on the receiving face of the rocking support piece.
According to the invention, since the serrated portion with serrations arranged in the paper sheet feeding direction is formed on the receiving face of the rocking support piece, even when the recording paper sheets are inserted into the paper sheet feeding apparatus attended with an impact force, the serrated portion securely supports the lower edge of the inserted paper sheets with the serrations acting to prevent the recording paper sheets from slipping and riding over the receiving face of the rocking support piece. This structure further enhances the function of reliably feeding the recording paper sheets one by one even when the recording paper sheets are inserted into the paper sheet feeding apparatus attended with an impact force.
The invention also provides a recording apparatus comprising:
one of the paper sheet feeding apparatuses described above; and
a print head for printing on a recording paper sheet at a position downstream of the bottom plate of the paper sheet feeding apparatus as viewed in the paper sheet feeding direction.
According to the invention, since the recording apparatus is equipped with the paper sheet feeding apparatus that can reliably feed the recording paper sheet one by one, wastage of recording paper sheets is avoided when printing on a recording paper sheet by keeping a plurality of recording paper sheets from being fed simultaneously.